Pneumatic rapper

ABSTRACT

A pneumatic rapper has the upper end of a guide tube arranged to face an anvil operatively mounted on an object to be rapped. A ball hammer is disposed within the guide tube and is arranged to be propelled against the anvil. A concentric outer tube surrounds the guide tube for a portion of its length to define an annular accumulator chamber therebetween. A diaphragm valve is operatively mounted on the lower end of the outer tube and is arranged to have a central portion of its upper face close the open lower end of the guide tube to prevent pressure in the accumulator chamber from entering the guide tube. A control chamber exposes the diaphragm to a differential pressure to force the diaphragm to close the open lower end of the guide tube. Pressure in the control chamber may be selectively exhausted to flex and displace the diaphragm, such operation being effective to rapidly admit pressure from the accumulator chamber to the guide tube to propel the ball hammer against the anvil and to impart an impact to the object. A recoil spring functions to absorb the reactive energy on the diaphragm as the ball hammer is propulsively accelerated toward the anvil.

United States Patent Bronlrman [4-51 Aug. 27, 1974 1 1 PNEUMATIC RAPPER [75] Inventor: Roger S. Brookman, East Aurora,

[73] Assignee: American Precision llndustries, inc,

Buffalo, NY.

[22] Filed: June 28, 1973 [21] Appl. No.: 374,813

Primary Examiner-James A. Leppink Attorney, Agent, or Firm-Sommer & Sommer [5 7] ABSTRACT A pneumatic rapper has the upper end of a guide tube arranged to face an anvil operatively mounted on an object to be rapped. A ball hammer is disposed within the guide tube and is arranged to be propelled against the anvil. A concentric outer tube surrounds the guide tube for a portion of its length to define an annular accumulator chamber therebetween. A diaphragm valve is operatively mounted on the lower end of the outer tube and is arranged to have a. central portion of its upper face close the open lower end of the guide tube to prevent pressure in the accumulator chamber from entering the guide tube. A control chamber exposes the diaphragm to a differential pressure to force the diaphragm to close the open lower end of the guide tube. Pressure in the control chamber may be selectively exhausted to flex and displace the diaphragm, such operation being effective to rapidly admit pressure from the accumulator chamber to the guide tube to propel the ball hammer against the anvil and to impart an impact to the object. A recoil spring functions to absorb the reactive energy on the diaphragm as the ball hammer is propulsively accelerated toward the anvil.

17 Claims, 7 Drawing Figures PNEUMATIC RAPPER 1. Field of the Invention The present invention relates to a pneumatic rapper for imparting an impact to an object.

2. Description of the Prior Art In general, dust collectors operate to separate solid or particulate material from a contaminated entrance gas and to exhaust the cleaned gas to the atmosphere or to other ductwork. Many of such dust collectors have a hopper to direct or funnel the gravity fall of such separated material toward a lower outlet chute or screw conveyor by which it may be removed.

In practice, however, it has'been found that the sepa rated particulate material often tends to collect or build-up on the inclined interior surfaces'of the hopper and thereby impede the desired descent on such material. Such collections may be particularly pronounced where the separated solids are ionized or where particle laden hot gas enters the dust collector with a high degree of water vapor such that moisture condensation is a problem. It is, often possible to periodically rap or impact the hopper to dislodge such accumulations of particulate material adhering to these interior hopper surfaces.

As general desirable design criteria, a rapper -to impact an object, such as a dust collector hopper, should be efficient. be simple in structure and operation, have a long life, be capable of automatic operation, and impart pronounced primary impacts to the object. The rapper should additionally be capable of absorbing the I reactive energy to minimize the unintentional damping of the primary impacts and to improve the fatigue life of the rapper.

Others have provided pneumatic rappers but, as pointed out herebelow, their designs and structures are not believed to satisfy all of the above design criteria. Owen (US. Pat. No. 2,518,995) provided a pneumatic rapper having a ball hammer positioned within an inner guide tube and arranged to be propulsively accelerated toward an anvil. While Owen provided a .form of pressure reservoir surrounding the guide tube, his oeration comprehended a relatively slow rise of the ball followed by a relatively rapid acceleration toward the anvil. Specifically, Owen admitted a pulse of compressed air to the reservoir which itself was vented. The guide tube was provided with two restrictive openings near its lower end to cause the ball to initially rise at a relatively slow rate. Only when the ball had risen sufficiently to close the reservoir outlet ports was the ball rapidly accelerated toward the anvil. Thus, Owen provided a two-,

stage sequential operation. Moreover, Owen provided no means or structure to absorb the reactive energy.

Gately (US. Pat. No. 3,605,915) provided another type of pneumatic rapper in which a compressed air pulse was admitted through a relatively small area fitting to drive a piston hammer toward an anvil. Howarea valve to act on a piston hammer. Dawson did not provide structure to absorb the reactive energy.

Finally, Pennington (U.S. Pat. No. 3,030,753) provided a pneumatic rapper wherein a piston hammer was caused to automatically oscillate in a chamber to produce vibrations of low intensity and high frequency. While Pennington did provide structure to reduce damping, his piston was caused to act against a return spring, thereby reducing the overall efficiency of his system. I

SUMMARY OF THE INVENTION The present invention relates to an improved pneumatic rapper for imparting pronounced impacts to an object.

The inventive pneumatic rapper includes an anvil operatively mounted on an object and arranged to transmit impacts or vibrations thereto. An inclined guide tube has an open upper end arranged to face the anvil and has an open lower end arranged below the upper end. Hammer means, such as a spherical ball hammer, are disposed within the guide tube for axial movement therealong. The force of gravity constantly urges the hammer means toward the lower end of the guide tube. An outer tube is arranged to surround the guide tube for a portion of its length to define an accumulator chamber therebetween. A closure plate joins the upper ends of the guide and outer tubes. The outer tube has a lower end arranged adjacent the lower end of the guide tube. Valve means, such as a flexible diaphragm, are arranged to act between the lower ends of the guide and outer tubes to block communication of the accumulator chamber from the interior of the guide tube. The valve means may be operated to rapidly admit pneumatic pressure from the accumulator chamber to the guide tube through the open lower end thereof to propel the hammer means against the anvil and to impart a pronounced impact thereto. Control means are arranged to selectively operate the valve means.

The control means includes a control chamber arranged to exert a pressure on a diaphragm surface opposing the force exerted by pressure in the accumulator chamber. Pressure in the control chamber may be selectively vented to operate the diaphragm. In one embodiment, a restrictive opening is provided through the diaphragm to permit the pressures in the accumulator and control chamber to equalize after a period of time. In another embodiment, pressure is independently supplied to the accumulator and control chambers.

The lower end of the guide tube may be additionally provided with a seat member and the upper face of the diaphragm may be provided with a seat member to insure an effective sealing engagement therebetween when the diaphragm is closed.

The invention may further include recoil means, such as a compression spring, arranged to absorb the reactive energy created as the hammer means is accelerated toward the anvil.

Accordingly, one object of the present invention is to provide an improved pneumatic rapper, capable of automatic operation, in which a ball hammer is propelled against an anvil to impart pronounced impacts or raps to an object.

Another object is to provide a pneumatic rapper wherein pressurized pneumatic fluid may be rapidly admitted to a guide tube to accelerate a hammer towards an anvil.

Another object is to provide a pneumatic rapper having a relatively large volume reservoir capable of storing pressurized pneumatic fluid used to propel a ball hammer.

Still another object is to provide a pneumatic rapper which is'simple in both design and operation and yet highly efficient for the purpose of rapping an object.

These and other objects and advantages will become apparent from the foregoing and ongoing specification, the drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the inventive pneumatic rapper shown exteriorly mounted on an inclined wall panel of. a dust collector hopper and operative to impart an impact thereto shake down solid material adhering to the interior surfaces of the hopper.

FIG. 2 is a fragmentary longitudinal sectional view of the inventive pneumatic rapper, taken on line 2-2 of FIG. 1, and particularly illustrates the internal structure of the pneumatic rapper at rest before the ball hammer is propelled against the anvil, it to be appreciated that the axis of the pneumatic rapper is shown vertical in FIG. 2 rather than at an angle inclined both to the vertical and horizontal as depicted in FIG. 1.

FIG. 3 is a fragmentary vertical sectional view thereof, taken on line 3-3 of FIG. 2, illustrating the internal structure of the pneumatic rapper as the valve means is operated to propulsively accelerate the ball hammer toward the anvil.

FIG. 4 is a fragmentary horizontal transverse sectional view thereof, taken on line 4-4 of FIG. 2, de-

' picting the cross sectional configuration of the accumutional view of such modified embodiment, taken on line 77 of FIG. 6, illustrating the internal structure of the modification at rest and particularly showing the modified control means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Preferred Embodiment (FIGS. 1-5) Referring to FIG. I, the inventive pneumatic rapper is generally indicated at 10 and, for greater clarity in understanding its practical utility, is shown exte'riorly mounted on an inclined lower panel 11 of a dust collector hopper assembly 12. However, at the outset it should be clearly understood that the utility of the present invention is not so'limited to the specific applica tion or environment illustrated in the drawings; rather, the inventive pneumatic rapper enjoys general utility and may be employed to impact other structures and objects or to impart vibrations thereto. Similarly, the term vibrations as used herein should not be construed as limiting either the amplitude or frequency of the oscillations imputed to the best mode herein described, as the present invention comprehends a wide range and variation in such parameters to accomplish a functionally similar end result.

In FIG. 1, the hopper assembly 12 is depicted as including four planar isoscles trapezoidal side panels, severally indicated at 11, the non-parallel edges 13 of which are suitably joined together, as by welding, to define a hopper assembly having a large area rectangular upper mouth 14 and a smaller area rectangular lower mouth 15. The environment illustrated in FIG. 1 depictes this hopper upper mouth 14 as being connected to ther structure 16 from which separated particulate material may be supplied. Thus, the hopper assembly 12 broadly functions to direct or funnel the gravity fall of such particulate material toward the lower mouth 15. In the well known and conventional manner, the lower mouth 15 may be provided with a door or gate (not shown) or be connected to other structure (not shown) to permit removal of such collected material.

In practice, it has been experienced that the particulate material may tend to collect or build-up on the interior inclined surface of the hopper and thereby impede the desired descent of such material. This effect may be particularly pronounced where the separated solids are ionized or where particle laden hot gas contains a high degree of water vapor such that condensation within the dust collector is a problem. In the environment shown and described, the inventive pneumatic rapper 10 functions to impact or vibrate the hopper assembly to dislodge or shake free these accumulations of collected or caked material adhering to the interior surfaces of the inclined hopper panels.

In FIGS. 2 and 3, the pneumatic rapper 10 is shown as broadly including a first subassembly 18 mounted on the object, and a second subassembly 19 movable relative to the first subassembly for a purpose hereinafter explained.

The first subassembly includes an anvil 20 and mounting means 21 operatively mounting the anvil to the object to transmit impacts or vibrations from the anvil to the object, and may additionally include one or more guide rods 22. The anvil 20 is shown as being a horizontal rectangular plate-like member having planar upper and lower faces 23, 24, respectively, and provided with a central vertical through hole 25 and four vertical mounting holes 26 symmetrically arranged adjacent the four corners of the anvil. A lower portion of the anvil adjacent central hole .25 extending upward from lower anvil face 24 is shown chamfered at 28 to provide a frusto-conical striking surface or seat on the anvil converging upwardly toward the object. After repeated operation, this frusto-conical striking surface may deform to the specific contour of the hammer.

The mounting means 21 is shownas being a generally U-shaped channel or mounting member having a horizontal web portion 29 and spaced left and right flange portions 30, 31, extending vertically upward from horizontal planar upper surface 32 of web portion 29. These flange portions or leg elements 30, 31 may be provided with large area openings 33 therethrough to permit lateral access to the interior of the channel (FIGS. 1 and 3). The upper or distal ends 34 of leg elements 30, 31 are arranged to be mounted or secured to a hopper panel 11 as by weldments 35 (FIG. 1). The web portion 29 has a horizontal planar lower surface 36 arranged to be covered by the anvil upper face 23, and

is also provided with a central vertical through hole 38 arranged to register with central anvil hole 25, and four rectangularly-spaced vertical through holes 39 arranged to register with the four anvil mounting holes 26. As best shown in FIGS. 1-3, two bolts 40 are passed through'a diagonally opposite pair of aligned holes 26,

. 39 to have their hex heads 41 contact the lower anvil face 24 and are severally provided with a pair of nuts 42 which may be suitably tightened against the upper surface 32 of the web portion 29 to rigidly mount the upper anvil face 23 against the channel web lower surface 36, thereby to transmit impacts from the anvil to the object. While the drawings illustrate the pneumatic rapper as being exteriorly mounted on a dust collector hopper, it should be understood that the mounting means may also'be employed to operatively connect the pneumatic rapper with other objects, such as rods, electrodes, and the like, arranged within a dust collec tor or other structure to accomplish a similar result.

The first subassembly 18 may additionally include a pair of guide rods 22 arranged through the other pair of diagonally opposite aligned holes 26, 39. As best shown in FIGS. 2 and 3, these cylindrical guide rods 22 are vertically positioned and are severally provided with exteriorly threaded upper and lower end portions 43, 44, respectively. The upper end portions 43 receive a pair of upper nuts 45 arranged to act on the upper surface-32 of web portion 29. Similarly, the lower projecting rod parts or end portions 44 receive a washer 46 and a pair of lower nuts 48 for a purpose later explained.

' The second subassembly 19 is movable relative to the first subassembly l8 and broadly includes an inner. guide tube 49, a concentric outer tube 50, closing means 56, and valve means 51. The guide tube 49 is depicted as having cylindrical inner and outer surfaces 52, 53, respectively, an open upper end or mouth 54 spaced from anvil chamfered surface 28 to provide vent means for exhausting pneumatic pressure from the interior of the guide tube, and an open lower end or mouth 55 arranged below the upper end. The closing means 56 is shown as being a horizontal rectangular plate having its horizontal planar upper surface 58 spaced from and arranged to face the lower anvil face 7 24, and provided with a central large diameter vertical hole 59 through which the guide tube upper end 54 is 7 passed and secured by a circular weldment 60. Plate 56 is also shown provided with two vertical through holes 61 arranged adjacent diagonally opposite corners to accommodate passage of guide rods 22. The spacing of plate 56 from the anvil is maintained by the presence of bolt heads 41 therebetween and, additionally, by a pair of thickened flat washers 62 arranged to encircle portions of the guide rods 22 between the anvil 20 and plate 56. A relatively large'diameter annular groove 63 extends into plate 56 from its horizontal planar'lower surface 64.

A relatively large diameter cylindrical outer tube 50 is concentrically arranged to encircle the guide tube 49 for a portion of its length and is shown as having its open upper end 65 sealingly secured in groove 63 by a circular weldment 66, and having its open lower end or mouth 68 arranged laterally adjacent the lower end 55 of the guide tube. As best shown in FIGS. 1, 3 and 4, a fitting 69 communicates with the annular accumulator chamber 70 between the guide and outer tubes, and is operatively connected via conduit 71 to a suitable source of pressurized pneumatic fluid, such as an air compressor (not shown). Thus, fitting 69 and conduit 71 function as means for introducing pressurized pneu matic fluid from-the source thereof to the accumulator chamber 70. Specifically, accumulator chamber functions as a large volume pressure reservoir and is bounded by surface 64 of plate 56, the inner cylindrical surface of outer tube 50, and the outer cylindrical surface 53 of guide tube 49.

A horizontal rectangular lower plate 72 has a large diameter annular groove 73 extending upwardly from its horizontal planar upper surface 74 and is provided with a central large diameter vertical through hole 75, a plurality of vertical through holes 76 arranged in a bolt circle concentric with hole 75, and two diagonally opposite vertical through holes 78 arranged adjacent opposite corners of plate 72 to slidably accommodate passage of guide rods 22 therethrough. The lower lip of plate 72 surrounding central hole is shown rounded at 79 to provide a smooth continuous surface. As best shown in FIGS. 2, 3 and 5, the open lower end 55 of guide tube 49 is sealingly secured in annular groove 73 by a circular weldment 80 therearound.

The valve means 51 is arrange-d to close the lower end of accumulator chamber 70 to block communication thereof with the interior of the guide tube 49 through the open .lower end 55 thereof and is selectively operable to unblock such communication so as to allow pressurized fluid from the accumulator chamber to enter the guide tube below the hammer for propelling the hammer toward the anvil. Specifically, the valve means 51 includes a horizontal circular flexible diaphragm 81, made of any suitable material such as rubber, having a' marginal portion of its horizontal upper face 82 arranged to engage a portion of the horizontal planar lower surface 83 of plate 72. The diaphragm 81 is also provided with a. plurality of vertical through holes 84 arranged in a bolt circle and which may be aligned with the circularly spaced holes 76 through plate 72.

Finally, a horizontal rectangular housing or cover 85 is arranged to have its horizontal planar upper surface 86 act on the marginal portion of the horizontal dia phragm lower face 88, and is provided with two vertical through holes 89 adjacent a pair of its diagonally opposite corners to slidably accommodate passage of guide rods 22 therethrough. Housing 85 is also provided with a plurality of vertical through holes'87 arranged in a bolt circle to register with aligned holes 84, 76 of the diaphragm 81 and plate 72, respectively. A corresponding plurality of bolts 40 may be passed through the aligned holes 76, 84, 87 of the several bolt circles to have their head portions 91 act on the horizontal planar lower surface 92 of the housing. The threaded ends of the bolts extend beyond the upper surface 74 of the plate 72 and are severally arranged to receive nuts 93 which may be selectively tightened to compress and sealingly mount the marginal portion of the diaphragm 811 between the plate 72 and housing 85. This housing is provided with an upper recess 98 which extends downward from the upper surface 86 thereof and a lower central recess 99 which extends further into the housing. These recesses 98, 99 in the housing form a relatively small volume control chamber 100 with the diaphragm lower face 88. Thus, housing 85 functions as control means for the valve means and includes means providing a control chamber 100 on the side of the diaphragm opposite from the guide tube and pro viding an area of exposure of this side of the diaphragm greater than the area of exposure of the other side of the diaphragm to the interior of the accumulator chamber when the valve means is closed. A passageway 101 extends vertically through the housing and communicates the control chamber 100 with a solenoid valve 102 exteriorly mounted on the housing lower surface 92. In the first preferred embodiment, solenoid valve 102 is a two-way valve which may be selectively operated by an electrical command signal to vent pressure in the control chamber or to retain such pressure therewithin.

The invention may further include recoil means, such as compression springs 103, each encircling a portion of a guide rod 22 and arranged to act between washer 46 and the lower housing surface 92. These springs 103 are arranged to urge the second subassembly toward the anvil and to absorb the reactive forces when the valve means is operated, as later described. The recoil means may employ other forms of resilient members, other than springs 103, such as a flexible and resilient material sufficient to accomplish the above functions.

As best depicted in FIGS. 2 and 3, a lower portion of the guide'tube 49 is encircled by a horizontal flat washer 104 suitably secured to the guide tube by a circular weldment 105 therearound. A cylindrical tubular seat member 106 covers a lower portion of the guide tube and has its upper end 108 arranged to abut the lower annular face of washer 104 and has a marginal portion 109 and its open lower end 110 extended axially below the guide tube lower end 55.

The'diaphragm 81 is shown supporting a horizontal circular plate-like seal member 111 on its upper face 82 and a larger diameter circular plate 112 on its lower face 88. Aligned vertical through holes 113, 114, 115 are provided through the seal member 111, the diaphragm 81, and the plate 112, respectively, to accommodate passage of a bolt 116 therethrough. Nut 118 may be threaded onto the exposed upper end of bolt 116 and suitably tightened to compress a central portion of the diaphragm between the seal member 111 and plate 112. I presently prefer that the seal member be formed of a relatively rigid material to influence flexure of the diaphragm and to provide an effective seal with the relatively deformable seat member 106.

A restrictive opening 119 is shown provided through the seal member-diaphragm-plate subassembly to permit pressure in control chamber 100 to equalize with the pressure in accumulator chamber 70 after a period of time. Passageway 119 serves as means for introducing pressurized pneumatic fluid into control chamber 100. Valve 102 functions as selectively operable means for venting'such control chamber 100 to atmosphere thereby rapidly to reduce the pressure therein.

A spherical ball hammer 120 is arranged within the guide tube 49 for vertical, longitudinal movement there-along. A clearance of several thousands of an inch is provided between the diameter of the ball and the inner diameter of the guide tube to insure its freedom of movement within the guide tube. Since, in operation, the lower end 55 of the guide tube is arranged below the upper end thereof, the force of gravity constantly urges the hammer to rest against the upper end of bolt 116 near the lower tube end.

In the best mode herein described, I presently prefer that the guide tube 49 have a cylindrical cross-section. However, other cross-sections of the guide tube may be employed with other hammer configurations. As used herein, hammer specifically includes a ball hammer, a piston hammer, and equivalents thereof. The outer tube need not necessarily be cooperatively configured or concentrically arranged with the guide tube. For example, the guide tube may have a cylindrical crosssection while the outer tube may have a hexagonal or other configuration. It is my express desire that the several elements recited in the claims be construed in their broadest sense and not be limited to the specific structure of the presently preferred embodiments shown and described herein.

Operation of the First Preferred Embodiment (FIGS. l-5) The operation of the first preferred embodiment is readily perceived by a visual comparison of FIGS. 2 and 3. During such operation, compressed air is continuously supplied to the accumulator chamber from its source via conduit 71 and fitting 69. When the solenoid valve 102 is commanded to the closed position, compressed air in the accumulator chamber 70 enters the control chamber through opening 119, the pressures in such chambers equalizing after a period of time; The control chamber 100 exposes this pressure against a larger area portion of the diaphragm lower face 88 than the accumulator chamber 70 exposes against the annular area of the diaphragm upper face 82. Thus, equal pressures in the control and accumula tor chambers exert an upward differential force urging the diaphragm to close, the seal member 111 moving into sealing engagement with the lower end of seat member 106 and thereby closing off the exhausting upward flow of air through the guide tube. Such valve closing force is sufficient to support the weight of ball hammer when resting on diaphragm bolt 49, as shown in FIG. 2.

Upon suitable electrical command, solenoid valve 102 may be actuated to its open position to rapidly vent or exhaust the pressure in control chamber 100. When the downward force produced by the pressure in the accumulator chamber 70 acting on the projected annular area of the diaphragm upper face 82 is greater than the opposing upward force exerted by the descreasing pressure in the control chamber 100 acting on the larger area diaphragm lower face 88, the diaphragm 81 will flex or deform to the position indicated in FIG. 3. Such displacement of the diaphragm is effective to rapidly admit a large volume of compressed air from the accumulator chamber to the now open lower end 55 of the guide tube. This high volume pulse of compressed air acts on the underside of ball hammer 120 and propulsively accelerates it vertically upward to impact upon the chamfered seat surface 28 of the anvil and to impart vibrations to the anvil, the mounting means, and to the hopper 12.

Since for every action, there is an equal and opposite reaction, the force produced by accelerating the large mass of the ball hammer toward the anvil will be opposed by an opposite force of like magnitude acting on the second subassembly. This reactive force causes the second subassembly to move vertically downward with respect to the first subassembly and the energy of this reactive force is absorbed by compressing recoil springs 103. Thus, the recoil means functions to absorb the reactive energy and thereby decreases the reactive fatigue on the structure.

Upon suitable electrical command, solenoid valve 102 may again be moved to the closed position to retain pressure within the control chamber and to return the apparatus to the position and condition shown in FIG. 1. The solenoid valve 102 may be either manually or automatically operated at periodic intervals to repeatedly impact the object.

Construction and Operation of the Second Preferred Embodiment (FIGS. 6 and 7) A modified embodiment of the inventive pneumatic rapper is illustrated in FIGS. 6 and 7 in which identical reference numerals indicate corresponding elements, members, and portions heretofore described.

The principal changes of this modified embodiment reside in the elimination of the bleed opening 119 through the diaphragm 81 and the provision of an alternate form of pressurizing the control chamber 100 and means for selectively venting the same.

As best shown in FIG. 6, compressed air is delivered from a suitable source (not shown) via conduit 12] and is supplied to the accumulator chamber 70 through branch conduit 122, variable valve 123, delivery conduit 124, and fitting 125. Similarly, compressed air in supply conduit 121 is delivered to control chamber 100 through another branch conduit 126, three-way solenoid valve 128, delivery conduit 129, and fitting 130. Under influence of a suitable electrical command signal, solenoid valve 128 may be selectively operated to admit compressed air from the source thereof to the control chamber 100, to retain such pressurized fluid within the control chamber, or to block such supply and vent or exhaust fluid within the control chamber to the atmosphere.

As above noted, the opening 119 in the diaphragm 81 has been eliminated in this modification such that, at all times, this diaphragm functions to sealingly isolate fluid in the accumulator chamber 70 from fluid in the con trol chamber 100 (FIG. 7). This modification operates substantially in the same manner as the first preferred embodiment previously described.

Referring toFlG. 7, compressed air may be selectively admitted through solenoid valve 128 to control chamber 100 to act on the large area lower face 88 of the diaphragm. Such pressurized fluid may also be admitted to accumulator chamber 70 through fitting 125 to act on the smaller annular area of the diaphragm upper face 82. Equal pressures in the control and accumulator chambers will act on their respective opposite diaphragm areas, such pressure acting on the greater differential area of the lower face 88 causing the seal member 111 to move into sealing engagement with the seat member 106 to close the lower end 55 of the guide tube and support ball hammer 120, as shown inFlG. 7.

The solenoid valve 128 may then be moved to its vent" position to exhaust compressed air from the control chamber. As this pressure decreases, the downthe ball hammer towards the anvil. The variable valve 123 may be suitably adjusted to regulate the pressure admitted to accumulator chamber for adjusting the propulsive force applied to the underside of ball hammer and hence the parameters of the impacts or vibrations imparted to the anvil.

From the foregoing description, it is readily apparent that the pneumatic rapper herein disclosed is both simple and yet highly effective to impact or rap an object. While the disclosed embodiments constitute presently preferred forms of the invention, it should be understood that other forms achieving like objects and advantages might also be adopted without departing from the spirit of the invention which is defined by the following claims.

What is claimed is:

1. A pneumatic rapper for impacting an object, comprising:

an anvil mountable on said object;

a hammer movable with respect to said anvil for striking the same;

a guide tube for guiding said hammer in its movement relative to said anvil and inclined in use so that gravity moves said hammer toward its lower end which is remote from said anvil;

vent means for venting the interior of said guide tube proximate said anvil;

an outer tube surrounding said guide tube in spaced relation to said guide and providing an accumulator chamber therebetween;

means closing the end of said chamber adjacent said anvil;

means for introducing pressurized pneumatic fluid into said chamber; and

valve means arranged to close the other end of said chamber to block communication thereof with the interior of said guide tube at said lower end thereof and selectively operable to unblock such communication so as to allow pressurized fluid from said chamber to enter said guide tube below said hammer and propel the same toward said anvil.

2. The pneumatic rapper according to claim 1 wherein said guide tube and outer tube have circular cross-sections and are concentrically arranged to detime said chamber therebetween having an annular cross-section.

3. The pneumatic rapper according to claim 1 wherein said valve means includes a diaphragm having a marginal portion sealingly mounted on said outer tube and having a central portion arranged to sealingly engage said lower end of said guide tube.

4. The pneumatic rapper according to claim 3 and further comprising a seat member covering a portion of i said guide tube and having a marginal portion extending axially beyond said lower end thereof, said seat member arranged to be engaged by said central portion of said diaphragm when said valve means is closed to block communication between said lower end of said guide tube and said chamber.

5. The pneumatic rapper according to claim 4 and further comprising a seal member mounted on said central portion of said diaphragm and arranged to move into and out of sealing engagement with said marginal portion of said seat member.

6. The pneumatic rapper according to claim 5 wherein said seal member is arranged on said central portion to influence flexure of said diaphragm when said valve means is operated.

7. The pneumatic rapper according to claim wherein one of said seat and seal members is relatively rigid and the other of such members is relatively deformable.

8. The pneumatic rapper according to claim 1 and further comprising:

control means for operating said valve means including means providing a control chamber on the side of said diaphragm opposite from said guide tube and providing an area of exposure of said side of said diaphragm greater than the area of exposure of the other side of said diaphragm to the end of the space between said tubes when said valve means is closed, means for introducing pressurized pneumatic fluid into said control chamber, and selectively operable means for venting said control chamber.

9. The pneumatic rapper according to claim 8 wherein said means for introducing pressurized fluid into said control chamber is provided by an opening through said diaphragm establishing communication between said chambers.

10. The pneumatic rapper according to claim 9 wherein said selectively operable means for venting said control chamber comprises a two-way valve.

11. The pneumatic rapper according to claim 8 wherein saidselectively operable means comprises a three-way valve, one way of which is arranged to vent said control chamber and another way of which is arranged to provide said means for introducing pressurized fluid into said control chamber.

12. The pneumatic rapper according to claim 1 wherein said guide tube, outer tube, closing means and valve means constitute a subassembly and further comprising:

recoil means operatively interposed between said anvil and subassembly to absorb reactive energy created as said hammer is pneumatically driven toward said anvil. 13. The, pneumatic rapper according to claim 12 V wherein said recoil means comprises:

wherein said anvil is provided with a seat to receive the impact of said hammer.

16. The pneumatic rapper according to claim 1 wherein the upper end of said guide tube is spaced from said anvil to provide said vent means for the interior of said guide tube proximate said anvil.

17. A pneumatic rapper for impacting an object, comprising:

a channel-shaped mounting member having a web from which leg elements extend;

an anvil plate secured to said web;

a ball hammer movable toward and away from said anvil plate;

a guide tube for guiding said ball hammer in its movement relative to said anvil plate and inclined in use so that gravity moves said hammer ball towards its lower end which is remote from said anvil, the other end of said guide tube being spaced from said anvil plate;

an outer tube surrounding said guide tube in spaced relation thereto to provide an accumulator chamber therebetween;

a closure plate proximate said anvil plate and secured to said tubes to close off one end of said accumulator chamber;

means for introducing pressurized pneumatic fluid into said accumulator chamber;

valve means arranged to close the other end of said accumulator chamber to block communication thereof with the interior of said guide tube at said lower end thereof, comprising a diaphragm extending transversely of said guide tube and said accumulator chamber, a cover sealingly securing the marginal portion of said diaphragm to said outer tube and having a central part spaced therefrom to provide a control chamber between said cover and diaphragm, the central portion of said diaphragm being arranged to sealingly engage said lower end of said guide tube;

means for introducing pressurized pneumatic fluid into said control chamber;

selectively operable means for venting said control chamber; and

recoil means comprising at least one guide rod secured to said mounting member and arranged paralle] to the axis of said guide tube and slidably extending through said cover laterally outside of said control chamber to provide a projecting rod part, and a coil spring surrounding said projecting rod part and operatively interposed between said cover and guide rod.

UNITED STA'IES PATENT OFFICE CERTIFICATE OF CORRECTION No. r r 686 d A gu 27 I 1974 I Rogr S. Brookman It is ergified that error appears-1n the abuse-identified pat ent and that said Letters Patent re hereby corrected as shown below:

Col. 1, line 44': "oeration" should be----operation---;

" Col. '2, line 47: "chamber" should, bechambers;

I Col. 2 line -52: "seat" should be--seal; i

I Col. 4", line 12: "ther" should be-other 1 Col. 4, line 23: "'-sur-face" should be- -'surfaces-"-; Col., 6, line 61: "downward" should be-.'-downwardly'-;I Claim 1, line 13: "'guide" should 'be-- guide,-'tube-; Claim l7,' line 10: "hammer ball" .shou-ld he -ball hammer-' I Signed", and sealed this Stdiday b mb gi97m Attestz: I v I I I- McCOY'II. GIBSON-JR. 1 c. MARSHALL nA N- Attesfliin'g Officer '7 v Commissioner of Patents I i Y- 

1. A pneumatic rapper for impacting an object, comprising: an anvil mountable on said object; a hammer movable with respect to said anvil for striking the same; a guide tube for guiding said hammer in its movement relative to said anvil and inclined in use so that gravity moves said hammer toward its lower end which is remote from said anvil; vent means for venting the interior of said guide tube proximate said anvil; an outer tube surrounding said guide tube in spaced relation to said guide and providing an accumulator chamber therebetween; means closing the end of said chamber adjacent said anvil; means for introducing pressurized pneumatic fluid into said chamber; and valve means arranged to close the other end of said chamber to block communication thereof with the interior of said guide tube at said lower end thereof and selectively operable to unblock such communication so as to allow pressurized fluid from said chamber to enter said guide tube below said hammer and propel the same toward said anvil.
 2. The pneumatic rapper according to claim 1 wherein said guide tube and outer tube have circular cross-sections and are concentrically arranged to define said chamber therebetween having an annular cross-section.
 3. The pneumatic rapper according to claim 1 wherein said valve means includes a diaphragm having a marginal portion sealingly mounted on said outer tube and having a central portion arranged to sealingly engage said lower end of said guide tube.
 4. The pneumatic rapper according to claim 3 and further comprising a seat member covering a portion of said guide tube and having a marginal portion extending axially beyond said lower end thereof, said seat member arranged to be engaged by said central portion of said diaphragm when said valve means is closed to block communication between said lower end of said guide tube and said chamber.
 5. The pneumatic rapper according to claim 4 and further comprising a seal member mounted on said central portion of said diaphragm and arranged to move into and out of sealing engagement with said marginal portion of said seat member.
 6. The pneumatic rapper according to claim 5 wherein said seal member is arranged on said central portion to influence flexure of said diaphragm when said valve means is operated.
 7. The pneumatic rapper according to claim 5 wherein one of said seat and seal members is relatively rigid and the other of such members is relatively deformable.
 8. The pneumatic rapper according to claim 1 and further comprising: control means for operating said valve means including means providing a control chamber on the side of said diaphragm opposite from said guide tube and providing an area of exposure of said side of said diaphragm greater than the area of exposure of the other side of said diaphragm to the end of the space between said tubes when said valve means is closed, means for introducing pressurized pneumatic fluid into said control chamber, and selectively operable means for venting said control chamber.
 9. The pneumatic rapper according to claim 8 wherein said means for introducing pressurized fluid into said control chamber is provided by an opening through said diaphragm establishing communication between said chambers.
 10. The pneumatic rapper according to claim 9 wherein said selectively operable means for venting said control chamber comprises a two-way valve.
 11. The pneumatic rapper according to claim 8 wherein said selectively operable means comprises a three-way valve, one way of which is arranged to vent said control chamber and another way of which is arranged to provide said means for introducing pressurized fluid into said control chamber.
 12. The pneumatic rapper according to claim 1 wherein said guide tube, outer tube, closing means and valve means constitute a subassembly, and further comprising: recoil means operatively interposed between said anvil and subassembly to absorb reactive energy created as said hammer is pneumatically driven toward said anvil.
 13. The pneumatic rapper according to claim 12 wherein said recoil means comprises: a guide rod operatively interposed between said anvil and subassembly and extending generally parallel to the axis of said guide tube for guiding relative movement between said anvil and subassembly; and resilient means operatively interposed between said guide rod and one of said anvil and subassembly.
 14. The pneumatic rapper according to claim 1 wherein said hammer is a spherical ball.
 15. The pneumatic rapper according to claim 1 wherein said anvil is provided with a seat to receive the impact of said hammer.
 16. The pneumatic rapper according to claim 1 wherein the upper end of said guide tube is spaced from said anvil to provide said vent means for the interior of said guide tube proximate said anvil.
 17. A pneumatic rapper for impacting an object, comprising: a channel-shaped mounting member having a web from which leg elements extend; an anvil plate secured to said web; a ball hammer movable toward and away from said anvil plate; a guide tube for guiding said ball hammer in its movement relative to said anvil plate and inclined in use so that gravity moves said hammer ball towards its lower end which is remote from said anvil, the other end of said guide tube being spaced from said anvil plate; an outer tube surrounding said guide tube in spaced relation thereto to provide an accumulator chamber therebetween; a closure plate proximate said anvil plate and secured to said tubes to close off one end of said accumulator chamber; means for introducing pressurized pneumatic fluid into said accumulator chamber; valve means arranged to close the other end of said accumulator chamber to block communication thereof with the interior of said guide tube at said lower end thereof, comprising a diaphragm extending transversely of said guide tube and said accumulator chamber, a cover sealingly securing the marginal portion of said diaphragm to said outer tube and having a central part spaced therefrom to provide a control chamber between said cover and diaphragm, the central portion of said diaphragm being arranged to sealingly engage said lower end of said guide tube; means for introducing pressurized pneumatic fluid into said control chamber; selectively operable means for venting said control chamber; and recoil means comprising at least one guide rod secured to said mounting member and arranged parallel to the axis of said guide tube and slidably extending through said cover laterally outside of said control chamber to provide a projecting rod part, and a coil spring surrounding said projecting rod part and operatively interposed between said cover and guide rod. 